MECHANISMS OF CARDIOVASCULAR COMPLICATIONS IN AIDS

这项拟议研究的主要长期目标是调查艾滋病患者因滥用可卡因而导致心血管并发症的机制。滥用可卡因引起的严重心血管并发症是众所周知的，但其分子机制尚未阐明。细胞因子在内皮细胞和心肌细胞功能的正常调节中发挥着重要作用。越来越多的证据表明，HIV-L的Tat蛋白可以改变细胞的基因表达和信号转导途径，并能诱导肿瘤坏死因子α和IL-1β等细胞因子的形成。初步数据表明，肿瘤坏死因子α可损害心血管功能，而可卡因的存在会加剧心血管功能。因此，我们将通过以下具体目的来验证TAT和细胞因子(TNFα和IL-1β)与可卡因及其代谢物联合可导致艾滋病患者心血管并发症的假设：(L)确定可卡因及其主要代谢产物在有无TNFα或IL-1β存在和不存在的情况下对人心肌细胞钙、钠、钾电流的调节作用；(2)研究TAT蛋白和/或炎性细胞因子在可卡因存在或不存在时对整合素表达和整合素介导的事件的调节作用，即内皮细胞迁移和白细胞与内皮细胞的黏附；(3)通过监测下列方面的变化来评估急性或长期使用可卡因和/或TNFpha的小鼠的心血管并发症：(A)通过监测全身动脉压和心输出量来测量全身血管阻力，(B)通过监测肺动脉压和心输出量来确定肺血管阻力，以及(C)通过测量左心室压的变化和变化率来评估左心室收缩能力；以及(4)确定Tat蛋白在调节心血管功能中的作用。TAT转基因和TNFpha受体敲除小鼠模型将被用于测试特定目标#3中指示的各种参数。拟议的研究将提供对在存在HIV感染的情况下可能导致可卡因引起心血管并发症的分子机制的深入了解。该提案的统一主题是确定TAT和炎症细胞因子在调节已在艾滋病患者中观察到的可卡因引起的心脏毒性效应中的作用。

The primary long term goal of the proposed research is to investigate the mechanisms responsible for cardiovascular complications from cocaine abuse in AIDS patients. Serious cardiovascular complications due to cocaine abuse are well known; however, the molecular mechanisms have not been delineated. Cytokines play a significant role in the normal regulation of the function of endothelial cells and cardiac myocytes. There is growing evidence that the Tat protein of HIV- l can alter cellular gene expression and signal transduction pathways and can induce the formation of cytokines such as TNFalpha, and IL-1beta. Preliminary data demonstrate that TNFalpha can compromise cardiovascular function which is exacerbated in the presence of cocaine. We will therefore test the hypothesis that a combination of Tat and the cytokines (TNFalpha and IL- 1beta) with cocaine and its metabolites can produce cardiovascular complications in AIDS patients, by investigating the following specific aims: (l) to determine the effects of cocaine and its major metabolites in modulating the Ca2+, Na+ and K+ currents in isolated human cardiac myocytes in the presence and absence of TNFalpha or IL-1beta; (2) to investigate the modulatory effects of Tat protein and/or the inflammatory cytokines in the presence or absence of cocaine on integrin expression and integrin mediated events, i.e., endothelial cell migration and leucocyte adhesion to endothelial cells; (3) to assess the cardiovascular complications in mice acutely or chronically treated with cocaine and/or TNFalpha by monitoring the changes in: (a) systemic vascular resistance measured by systemic arterial pressure and cardiac output, (b) pulmonary vascular resistance determined by monitoring pulmonary arterial pressure and cardiac output, and (c) left ventricular contractility by measuring changes and the rate of change in the left ventricular pressure; and (4) to determine the role of Tat protein in modulating cardiovascular function. The tat transgenic and TNFalpha receptor knockout mouse models will be used to test the various parameters indicated under specific aim #3. The proposed studies will provide an in-depth understanding of the molecular mechanisms that may be responsible for the cocaine-induced cardiovascular complications in the presence of HIV infection. The unifying theme of the proposal is to define the role of Tat and the inflammatory cytokines in modulating the cocaine induced cardiotoxic effects that have been observed in patients with AIDS.